Obscured by Clouds. The rough and ready blog of a cloud benighted biologist and amateur astronomer. Astroblog will cover my interests in astronomy, biology and Life, the Universe and Everything.

Sunday, February 17, 2013

Occultation of Jupiter, Monday 18 February, 2013

Evening sky
looking North-west as seen from Adelaide at 22:45 pm local daylight
saving
time on Monday February 18. This is just before the Moon covers Jupiter.
The inset shows Jupiter's Moons at 10:48 ACST, just before Ganymede is
covered by the Moon. Similar views will be seen elsewhere at the times
indicated in the table below. Click to embiggen.

A larger view of the same event simulated in Stellarium, just before Ganymede is occulted (covered) by the Moon at 10:48 ACST.

On the evening of Monday, February 18, the Moon will occult (cover)
Jupiter in Southern Australia (everywhere else sees it very close). It
will be quite spectacular with Jupiter's Moons being covered by the dark
side of the Moon just before Jupiter.

While the sight of Jupiter winking out behind the dark edge of the Moon
will be spectacular to the unaided eye, this is far better seen in binoculars, or better in
a small telescope.

As a bonus, many places will see the occultation of the 5th magnitude star Omega Tauri before the main event.

The event does occur around 11 pm or so (earlier in WA which has the best views again). It's pretty easy to see where it is happening (just look for the Moon). Note Ganymede disappears before Jupiter and the other Moons after.

At mid graze/occulation, the Moon will be quite low to the horizon, so
if you are using a telescope, make sure it has a clear horizon and can
travel down reasonably well. It is advisable to set up and practise on
the Moon and Jupiter a day or so before the event, so you are familiar
with your telescope set-up.

Set up at least half an hour ahead of time
so that you can be sure everything is working well and you can watch the
entire event comfortably (trying to focus your telescope on Jupiter moments before the occultation will cause a lot of unnecessary stress). Also, setting up early allows your eyes to adapt to the darkness.

If you are using binoculars, try leaning them on a fence or the back of a chair so that the don't wobble all over the place. Better yet, see if you can get a binocular mount, you won't regret it.This is also an opportunity to see Jupiter in the daylight. Using the Moon as your guide, you should be easily able to see Jupiter with the unaided eye 15 minutes before
Sunset, and 30 minutes before Sunset using binoculars. Make sure the Sun is hidden behind something big like a wall to avoid accidental exposure to the sun.

More posts on seeing planets in daylight (with hints and tricks), are here.

Went out to hand out washing just on dark and saw what looked like a star on the moon.... Thought it very weird so googled it and found your page. Thanks for the info... Excited to read what we just witnessed.

Thanks Ian, I have been outside watching it, and taking some photos.... just a little way north of Albany WA. There was a smidgin of cloud came over for the last few minutes, but still very visible! apart from the mozzies, it is very exciting!

tragically we ended up with cloud in Melbourne, but nonetheless did have the good fortune to see the start - and saw the moon turn orange as Jupiter started its pass behind - was the colour change to do with the occultation or the coincidence of grassfire smoke that has now obscured our view? Thanks for the post too by the way!

The orange colour is because the moon was lower in the sky- more scattering of the bluer light of dust particles. In your area, yes past fires increase the particle density. The current fire though only affects the light when the cloud of smoke is between you and the moon. Unless it was thin then it only blocked out the moon.

This was a unique sight in central Melbourne: the moon with Jupiter very close and both coloured a fiery orange due to the bushfire smoke from the north of the city. Unfortunately it was then totally covered.David Collins

In Melboune SE, It was an amazing sight to see last night, we had a clear sky & view. Curiously tonight, a patch of the night sky in cranbourne area had a green tinge to it. No visible clouds, or stars or moon, just this large patch of green tinge with a faint brightness? Wander if anyone else observes it.